@a77ay/better-auth-mikro-orm

MikroORM database adapter and entity generator for Better Auth.

🔌 Database Adapter  •  ⚡ CLI Entity Generator

Features

• 🔌 Native MikroORM Adapter: Seamlessly integrates with MikroORM's EntityManager, Identity Map, and Unit of Work.
• ⚡ Entity & Schema Generator: Generate MikroORM entities compatible with Better Auth core and all active plugins.
• 🗄️ Multi-Database Support: Full support for PostgreSQL, MySQL, MariaDB, SQLite, LibSQL, MongoDB, and custom drivers.
• 🚀 Optimized Relations: Batched queries for joined relations to prevent N+1 issues.
• 🔒 Type-Safe: Complete TypeScript support with automatic type inference.

Installation

# Using npm
npm install @a77ay/better-auth-mikro-orm @mikro-orm/core

# Using pnpm
pnpm add @a77ay/better-auth-mikro-orm @mikro-orm/core

# Using yarn
yarn add @a77ay/better-auth-mikro-orm @mikro-orm/core

# Using bun
bun add @a77ay/better-auth-mikro-orm @mikro-orm/core

Compatibility

| @a77ay/better-auth-mikro-orm | better-auth | @mikro-orm/core | | ------------------------------ | ------------- | ----------------- | | 0.x (latest) | ^1.7.0 | ^7.0.0 |

Quick Start

1. Adapter Setup

import { betterAuth } from "better-auth";
import { mikroOrmAdapter } from "@a77ay/better-auth-mikro-orm";
import { orm } from "./mikro-orm.config";

export const auth = betterAuth({
  database: mikroOrmAdapter(orm),
});

Pass your MikroORM instance, EntityManager, or a getter function. When passing orm, the adapter automatically uses RequestContext.getEntityManager() per HTTP request and falls back to orm.em for CLI commands and background scripts.

2. Schema / Entity Generation

Running the Generator

Use the package CLI to generate individual entity files and an index.ts barrel export:

# Using npx
npx @a77ay/better-auth-mikro-orm generate \
  --config ./src/auth.ts \
  --output ./src/entities/auth \
  --yes

# Using pnpm
pnpm exec @a77ay/better-auth-mikro-orm generate \
  --config ./src/auth.ts \
  --output ./src/entities/auth \
  --yes

Register in MikroORM

The generated index.ts exports each entity and a betterAuthEntities array. Register that array in your MikroORM configuration:

import { betterAuthEntities } from "./src/entities/auth";

export default {
  entities: [...betterAuthEntities],
};

Every Better Auth model must be registered as a MikroORM entity. Its tableName must match the corresponding Better Auth model name (including configured model renames or pluralization).

The adapter handles data access and transactions; MikroORM migrations remain responsible for creating and updating the database schema. After generating entities, use MikroORM's migration tooling to create and apply the database migration.

CLI Flags

• --config <path>: Better Auth config (default: ./src/auth.ts).
• --output <path>: Output directory (default: src/entities/auth).
• --style <style>: define-entity or decorators; overrides the adapter option.
• --casing <casing>: camelCase or snake_case; overrides the adapter option.
• --file-suffix <suffix>: Custom entity file suffix (e.g. .entity for user.entity.ts); overrides the adapter option.
• --yes: Overwrite generated files. Without it, existing generated files are protected.

Configuring Defaults in auth.ts

Instead of passing CLI flags every time, generator options such as entityStyle, casing, fileSuffix, and the default output directory can be configured directly in mikroOrmAdapter:

export const auth = betterAuth({
  database: mikroOrmAdapter(orm, {
    entityStyle: "define-entity", // "define-entity" (default) | "decorators"
    casing: "snake_case", // "snake_case" | "camelCase" (default)
    directory: "src/entities/auth", // Default CLI output directory
    fileSuffix: ".entity", // Optional file suffix: user.entity.ts (default: "")
  }),
});

Single-File Generation (Official Better Auth CLI)

If you prefer generating a single schema file instead of a modular directory, you can use the official Better Auth CLI:

# Using npx
npx auth@latest generate \
  --config ./src/auth.ts \
  --output ./src/entities/auth.ts \
  --yes

# Using pnpm
pnpm dlx auth@latest generate \
  --config ./src/auth.ts \
  --output ./src/entities/auth.ts \
  --yes

The adapter exposes the official Better Auth createSchema hook used by this command.

Configuration Options

The mikroOrmAdapter accepts the database instance or getter as its first argument and an optional options object as its second argument:

mikroOrmAdapter(em, options?)

| Parameter / Option | Type | Default | Description | | ------------------ | ---------------------------------------------------- | ------------------------ | --------------------------------------------------------------------------------------- | | em (1st arg) | MikroORM \| EntityManager \| (() => EntityManager) | Required | MikroORM instance, EntityManager, or getter returning the request-scoped instance. | | provider | DatabaseProvider | Auto-detected | Database provider ("postgresql", "sqlite", "mysql", "mongodb", or custom). | | casing | "snake_case" \| "camelCase" | "camelCase" | Naming convention for generated database columns. | | entityStyle | "define-entity" \| "decorators" | "define-entity" | Entity definition style (defineEntity fluent schema or @Entity() class decorators). | | fileSuffix | string | "" | Custom file suffix for entity files (e.g. ".entity" generates user.entity.ts). | | directory | string | "src/entities/auth" | Default output directory used by the package CLI. | | schemaFile | string | "src/entities/auth.ts" | Default output file path for CLI schema generation. | | debugLogs | boolean \| DBAdapterDebugLogOption | false | Enable Better Auth adapter debug logging. | | usePlural | boolean | false | Use plural table names for generated entities. | | transactions | boolean | true | Whether to execute multi-operation callbacks in a transaction. |

Development

This project uses Vite+ for tooling:

• Install dependencies:

  vp install

• Run tests (SQLite in-memory):

  vp test

• Type check, lint and format:

  vp check

• Build library:

  vp pack

License

MIT © A77AY